Windows are the most important component within building envelope to control both solar heat gain and thermal losses, but also to guarantee an optimal daylight level. Metal mesh are used in new and renovated buildings, especially in office building, as an external second envelope skin to enhance architecture design, to manage daylight levels and to control solar gains. The aim is the optimization of their position, compared to the façade raising plane, enhancing the metal mesh systems energy performance, increasing the comfort requirements and reducing the amount of used material to minimize costs. In order to evaluate their performances (mesh spacing and orientation) an estimation of the primary energy consumption for heating, cooling, lighting and daylight comfort has been carried out. The study case is a single 3 x 4 x 3m (W x L x H) office unit placed in Milan (Italy) under a single orientation (South). It has one wall facing outdoors, having a Window Wall Ratio (WWR) of 86%, and five surfaces, considered as adiabatic, because facing other internal offices (three wall, ceiling and floor). A three-step approach was carried out to assess a sensitivity analysis with Energy Plus and Radiance engine, managed with a parametric modelling approach (Rhinoceros and Grasshopper), evaluating shading systems performance. For all of the simulations have been calculated the total primary energy (for heating, cooling and lighting) and the principle daylight comfort index like (Daylight Factor, Useful daylight illuminance and Glare Analysis). In the first step the standard metal mesh system with different ratio between spacing and characteristic diameter (d/D equal to 0.2, 0.6, 1) has been analysed and compared with a standard façade solution such as low-e double glazing unit (DGU) alone and the same one coupled with an internal curtain. In a second phase the performance of metal mesh shading device with different tilt angle (-20°, -10°, 10°) were evaluated. In the third phase, a further system implementation was assessed decomposing the second phase system in smaller sub-systems using a hybrid solution with metal mesh and louvers. The results shows that considering only the total energy primary energy use the system that performs better is the metal mesh with d/D equal to 0.6 and a 10° tilt angle (from the façade raising plane). Instead evaluating also costs and internal comfort the hybrid system have a better behaviour.

ETFE membranes are generally used in architecture for large roofing and façade systems, because of their transparency and lightness compared to glass alternatives. Multilayer ETFE panels are used to improve single membrane systems performances, reducing thermal losses, by the use of an air gap between two or more ETFE foils, generally serigraphed or surface treated to reduce solar gains. Surface temperatures and global solar radiation strongly affects mean radiant temperature (MRT), and comfort perceived by a user facing a transparent envelope as well as solar gains strongly influences primary energy use for cooling in summer conditions.

Nowadays, building energy models use parametric analyses to optimize design strategies considering multiple variables. Integrated dynamic models combining design tool and visual programming language (VPL) and simulation tools to calculate building performance with BIM tool for the whole-building energy simulation have been adopted in the recent studies. Through these tools, it is possible to identify parametric systems, which become a “genome”, where a rapid comparison of different alternatives is possible through fitness criteria defined by design goals. The aim of the paper is to use this concept and the suitable parametric tools such as Grasshopper for Rhinoceros to handle variable hypotheses on users’ occupancy that influence building energy performance. The paper focuses on occupancy variability applying the methodology to a university building located in northern Italy in the University of Brescia Campus to evaluate how generative modelling can represent an adequate approach to energy simulation of occupant behaviour. Sensors are now monitoring the real occupancy trend of the case study building and different scenarios defined in the parametric model could be compared to the real weekly. Using parametric tool and GA (Genetic Algorithms) can be analysed hundreds of occupancy patterns in order to better understand the influence of the occupancy on the building energy use and at the same time evaluate different strategies to save energy.

Office buildings in contemporary architecture usually have a high value of window to wall ratio (WWR) determining transparent façade as the most important part of the building façade to control solar gains, thermal losses and visual comfort. Therefore, in order to fulfill strict National energy regulations and LEED requirements, façades require a proper balance between transparent and opaque or shaded surfaces to avoid overheating, optimizing daylighting aspects and outdoor perception. Concrete is usually used in building sector for primary structure or secondary structure of cladding solutions. With new concrete materials and innovative digital fabrication process is possible to rediscover concrete for high performance façade/shading solutions. The aim of this paper is the development of high performance concrete static shading system using computational design approach and its optimization, by genetic algorithms, based on several parameters such as radiation control, outdoor view and daylight indexes and energy performance.

Cities often show nighttime air temperatures higher by 3–4 °C than adjacent non-urban areas. This yields to cooling loads in average higher by 13% for urban than rural buildings. Here we assess the hygrothermal performance and the heating and cooling loads of a reference building representative of the Italian stock. We compare its performance calculated with hourly urban weather data (2002–2008) with the performance of the same building using a rural dataset instead. Milan’s Urban Heat Island reduces the heating loads by 12% and 16%, for the non-insulated and insulated building, respectively, while the cooling loads are increased by 41% and 39%. The urban building also shows de-humidification loads 74–78% lower than the rural building. Moreover, during the 2003 heat wave, the indoor air temperature is computed to be 1.5 °C–2.2 °C higher in a non-conditioned urban building than in the rural one. This increases the wakefulness, occupants’ vulnerability to overheating, and impacts the overall hygrothermal performance. Our findings highlight the need of a different design concept for urban with respect to non-urban buildings, even though they are, by law, in the same climate zone.

Wall finishes with high solar reflectance and thermal emittance, commonly known as cool walls, can reduce the exterior surface temperatures of façades, and consequently the building cooling energy needs and power demand, and lower the sensitivity to degradation. Aging, though, may affect their performance. To investigate this risk, we exposed for four years in Milan, Italy, two series of façade finish coats, white and beige, facing north and south, in vertical and vertical-sheltered position, and we measured their solar spectral reflectance and thermal emittance before and after aging. The solar reflectance of the white finish coats drops from 0.75 to 0.55 in four years, and from 0.46 to 0.38 for the beige coats, while the thermal emittance is unchanged. Then, for a typical residential building with white walls, we computed that the cooling energy needs increase with walls aging by 5% and 11%, respectively, with or without exterior wall insulation. The exterior surface temperature is increased even by 6 °C, and the number of sudden surface temperature variations in one hour is boosted. Finally, the moisture content in the external layers is reduced, showing the impact on the heat and mass balance because of the uncertainty in solar absorption due to aging.

Comfort control and assessment in open spaces is an issue widely treated in literature, as well as the effectiveness of possible mitigation strategies (green area, shadings etc.), measure and model validation procedures and the use of dynamic analysis tools. The aim of this paper is to identify and compare textile material for roofing, considering different properties such as tensile strength, embodied energy, cost and how their optical-radiative behavior affect comfort. Hence, for a selection of two types of textile that have different optical-radiative properties we simulated the air temperature and, in accordance with UTCI index, the hourly comfort of the users under a reference roofing structure. The effects of soiling on textile surfaces and how affects the decay of optical-radiative properties is already investigated. The performance decay analysis during time was carried out on a membrane made of polyester with a PVC coating and an additional protective PVDF layer. The fabric was selected in accordance with a preliminary performance comparison between different textile materials generally used for temporary and/or semi-permanent tent structures. Optical and radiative measurements at zero time were performed obtaining, in accordance with iso 9050 integrated values of 4.6% for transmittance and 80% for reflectance of the external surface. Later on the textile samples have been exposed outdoor on a sample holder and with different slope (horizontal, vertical and 45°). After 3 and 6 months of exposure, reflectance and transmittance measurements were measured again. Measurements have pointed out a decay of reflectance in the visible and infrared range by about 17% after 6 months of exposure (more pronounced for some exposures compared to other and more important in the visible range than in the infrared one).

The control of solar gains through transparent surfaces is the primary objective in order to reduce buildings’ cooling energy needs. Heat and luminous fluxes cannot be modulated only by single glazing; thus, the transparent surfaces are protected by an external shading element with different efficacy grades, in function of the material consistency, morphology, and handling typology. In steel and glass architectures, whose design is often experimental, there is a more and more frequent use of elements characterized by a three-dimensional matrix and a multi-directional performances, as for instance expanded metal or perforated metal sheets, micro and geosynthetic fabrics. The objective of this contribution is to determine, for several typologies of materials with 3D matrix, the optical-energetic behaviour and the correlation between geometry variation and performance, as a function of the angle of incidence of solar radiation. We selected 3 samples, and we measured their solar transmittance for angles of incidence from near normal to 60°. Then with numerical simulation we compared their performance and shading efficacy. The analysis carried out shows that solar transmittance does not always decrease with increasing angle of incidence. For the selected samples, the relative positioning of the texture (horizontal or vertical) affects the transmittance values: for angles smaller than 30° the samples orientation involves a performance variation up to 18%, over 30 ° this variation increases up to 43% for 60 °.